The purpose of this study was to evaluate the relationship between: 1) laboratory-determined cycling peak oxygen consumption (VO 2max ) and AS performance in a new underwater swim test (UWST), and 2) cycling VO 2max and ventilatory threshold (VT) in cycling and performance score during a simulated AS solo routine. Trained artistic swimmers (n=15, 15.8±0.8 yrs., height: 169.1±5.4 cm, body mass: 57.1±6.3 kg) completed (1) a maximal incremental cycle test to exhaustion to determine VO 2max , (2) the UWST which comprised 275 m of freestyle and underwater breaststroke, and (3) a simulated solo competition where artistic swimming elements were evaluated by five FINA judges. There was a significant correlation between mean element score and (i) VO 2max (48±4 mL . kg . min -1 , r=0.44, p =0.05), and (ii) UWST (r=-0.64, p =0.005). However, there was an insignificant relationship between cycling ventilatory threshold and mean element score (r=-0.36, p =0.10). In addition, the results demonstrate a significant relationship between HR at the ventilatory threshold and peak HR of the UWST (r=-0.64, p =0.014). The results of this study demonstrate that VO 2max is an important determinant of AS performance. In addition, the UWST appears to be a useful indicator of AS performance.